1. Field of the Invention
The present invention relates to a portable terminal, such as a cellular phone terminal, that is capable of outputting audio signals of music, videos, and the like to a plurality of external headphones, an audio output control method for controlling audio output to the plurality of external headphones, and an audio output control program.
2. Description of the Related Art
Headphone connectors of cellular phone terminals have been used, for example, only for so-called “hands-free” voice calls. However, since recent cellular phone terminals have a function of playing back music and videos, an increased number of people have come to use the above-mentioned headphone connectors in order to listen to music and video sounds.
It is assumed that listening to music or video sounds by using a headphone is performed by only a single user. Thus, for example, it is difficult for a plurality of people to enjoy listening to music or video sounds by using a single cellular phone terminal.
When music or video sounds are output via a loudspeaker provided in a cellular phone terminal, it is possible for many people to listen to the music or video sounds. However, in a case where the place where people listen to music or video sounds is, for example, a public space, outputting such sounds via the loudspeaker may trouble surrounding people.
Under such circumstances, a technique in which by providing a plurality of headphone connection terminals in a portable audio device and connecting headphones to the respective headphone connection terminals, a plurality of people are able to listen to music at the same time, has been proposed, for example, in Japanese Unexamined Patent Application Publication No. 2007-97007.
In addition, a cellular phone including two earphone jacks having an input/output function is disclosed, for example, in Japanese Unexamined Patent Application Publication No. 9-247249 (FIG. 1). In the cellular phone, an externally input audio signal that has been input from an external audio output device to one of the two earphone jacks can be switched to an audio signal output from an internal audio processing circuit and can be output to the other one of the two earphone jacks. That is, in a case where a call has arrived at the cellular phone while an externally input audio signal input from an audio output device to one of the earphone jacks is being output via the other one of the earphone jacks, the cellular phone switches the externally input audio signal to a ringing signal and outputs the ringing signal via the other one of the earphone jacks.